AWS Lambda Runtimes

AWS Lambda supports multiple languages through the use of runtimes. You choose a runtime
when you create a
function, and you can change runtimes by updating your function's configuration. The
underlying execution environment, which is shared by all runtimes, provides
additional libraries and environment variables that you can access from your function
code.

When your function is invoked, Lambda attempts to re-use the execution environment
from a previous invocation if
one is available. This saves time preparing the execution environment, and allows
you to save resources like
database connections and temporary files in the execution context to
avoid creating them every time your function runs.

A runtime can support a single version of a language, multiple versions of a language,
or multiple languages.
Runtimes specific to a language or framework version are deprecated
when the version reaches end of life.

To use other languages in Lambda, you can implement a custom runtime. The
Lambda execution environment provides a runtime interface for getting invocation
events and sending responses. You can deploy a custom runtime alongside your function
code, or in a layer.